model-routing

# Model routing `run.sh` reads three optional env vars and threads them into each `claude` invocation as `--model`. All default to unset, in which case the CLI default model is used (behaviour unchanged from a bare run). ## The three knobs - `CLAUDE_PLANNER_MODEL` — reserved for `/spec` workflows that draft PROMPT.md up front. Not read by the current `run.sh` loop, but claimed here so future planner passes bind to it. - `CLAUDE_EXECUTOR_MODEL` — used on the "do the next step" call. This is the workhorse; it runs on every iteration. Pick something cheap and fast. - `CLAUDE_JUDGE_MODEL` — used on the `/verify` call. Runs once per iteration to adversarially check the executor's diff. Pick a frontier model — a weak judge is worse than no judge. ## Recommended shape ``` planner = frontier (Opus-class, runs once at /spec time) executor = cheap-fast (Haiku-class, runs every turn) judge = frontier (Opus-class, runs every turn but on a small diff) ``` ## Example ```bash export CLAUDE_PLANNER_MODEL="claude-opus-4-7" export CLAUDE_EXECUTOR_MODEL="claude-haiku-4-7" export CLAUDE_JUDGE_MODEL="claude-opus-4-7" ./run.sh ``` ## The Elvis Executor+Judge finding A cheap executor paired with a frontier judge outperforms a frontier executor with no judge on long loops. The judge catches the executor's premature-victory claims that a mono-model run rationalises away when it runs out of context. Cost stays low because the judge only sees the diff, not the working history.